Book Image

Puppet 5 Cookbook - Fourth Edition

By : Thomas Uphill
Book Image

Puppet 5 Cookbook - Fourth Edition

By: Thomas Uphill

Overview of this book

Puppet is a configuration management system that automates all your IT configurations, giving you control of managing each node. Puppet 5 Cookbook will take you through Puppet's latest and most advanced features, including Docker containers, Hiera, and AWS Cloud Orchestration. Updated with the latest advancements and best practices, this book delves into various aspects of writing good Puppet code, which includes using Puppet community style, checking your manifests with puppet-lint, and learning community best practices with an emphasis on real-world implementation. You will learn to set up, install, and create your first manifests with version control, and also learn about various sysadmin tasks, including managing configuration files, using Augeas, and generating files from snippets and templates. As the book progresses, you'll explore virtual resources and use Puppet's resource scheduling and auditing features. In the concluding chapters, you'll walk through managing applications and writing your own resource types, providers, and external node classifiers. By the end of this book, you will have learned to report, log, and debug your system.
Table of Contents (16 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Using the in operator


The in operator tests whether one string contains another string. Here's an example:

if 'spring' in 'springfield'

The preceding expression is true if the spring string is a substring of springfield, which it is. The in operator can also test for membership of arrays as follows:

if $crewmember in ['Frank', 'Dave', 'HAL' ]

When in is used with a hash, it tests whether the string is a key of the hash:

$ifaces = {
  'lo'   => '127.0.0.1',
  'eth0' => '192.168.0.1'
}
if 'eth0' in $ifaces {
  notify { "eth0 has address ${ifaces['eth0']}": }
}

How to do it...

The following steps will show you how to use the in operator:

  1. Add the following code to your manifest:
if $::operatingsystem in [ 'Ubuntu', 'Debian' ] {
  notify { 'Debian-type operating system detected': }
} elsif $::operatingsystem in [ 'RedHat', 'Fedora', 'SuSE', 'CentOS' ] {
  notify { 'RedHat-type operating system detected': }
} else {
  notify { 'Some other operating system detected': }
}
  1. Run Puppet:
t@cookbook:~$ puppet apply in.pp
Notice: Compiled catalog for cookbook.example.com in environment production in 0.01 seconds
Notice: RedHat-type operating system detected

There's more...

The value of an in expression is Boolean (true or false) so you can assign it to a variable:

$debianlike = $::operatingsystem in [ 'Debian', 'Ubuntu' ]
if $debianlike {
  notify { 'You are in a maze of twisty little packages, all alike': }
}